The use of phosphorus-containing materials as flame retardants, corrosion inhibitors, adhesion promoters, and scale inhibitors is well known. Conventional phosphorus-containing additives are non-polymerizable and suffer from several drawbacks such as migration and leaching, leading to modification of adhesive, coating or film properties over time. Commercially available phosphorus-containing monomers, such as vinylphosphonic acid and ethylphosphonic acid monovinyl ester exhibit a reduced tendency for polymerization and give polymers with low molecular weight.
Commercially available alkylphosphates containing (meth)acrylic functionality show reduced hydrolytic stability, as the phosphate or methacrylate ester bond can be cleaved in the presence of water. This reduces their storage stability and limits their applications.
(Meth)acrylic phosphonic acids and esters are known to be more hydrolytically stable than analogous phosphate acids and esters. These monomers are also known for their flame retardant activity, scale inhibiting activity and imparting adhesive properties in coatings.
For example, U.S. Pat. Nos. 3,030,347 and 2,934,555 teach dialkylphosphonoalkyl acrylate and methacrylate copolymers and methods for preparation. The compounds are used in leather or textile finishes for imparting flame retardancy.
U.S. Pat. No. 3,884,628 teaches N-phosphonomethylacrylamide as flame retardant for textiles.
U.S. Pat. No. 3,989,772 discloses N,N-bis-(phosphonomethyl)-acrylamides. The compounds are alleged to be suitable as flame proofing agents.
U.S. Pat. No. 4,526,728 discusses phosphonate monomers for dyeing auxiliaries and scale inhibitors.
U.S. Pat. No. 3,351,617 discloses a condensation product of methylolacrylamide and β-(dimethylphosphono)-propionamide and the use of the formed monomer as a flame retardant in fabric treatment.
U.S. Pat. No. 4,650,591 discloses acrylamido-2-methylpropanephosphonic acid as a corrosion inhibitor and its use as a scale inhibitor.
PCT application no. WO03/035013 discloses self-priming dental adhesive compositions containing phosphonic acid moieties. The invention alleges adhesion to enamel and/or dentin with a bond strength of at least 8 Mpa.
It is known to apply (meth)acrylic phosphonic acids and esters directly to a surface such as a metal to promote adhesion. In some cases the (meth)acrylic phosphonic acids and esters are polymerized directly onto a surface via radiation curing in the presence of other monomers.
For example, U.S. Pat. No. 4,029,679 discloses phosphonate monomers as a metal primer.
U.S. Pat. No. 6,740,173 discloses the use of phosphonate oligomer and phosphonate monomers (phosphonated methacrylates) in a composition for preventing metal corrosion with binder and metal reactive additives.
Bressy-Brondino, C. et al, Journal of Applied Polymer Science 2002, 83(11), 2277-2287, discloses blends of poly(vinylidene fluoride) and copolymers of methyl methacrylate and dimethyl 2-methylacryloyloxyethylphosphonate as a coating on steel.
U.S. Pat. No. 6,436,475 discloses a process for treating zinc, magnesium or aluminum wherein an organic compound with at least one phosphoric or phosphonic acid group is applied onto the metallic surface.
U.S. Pat. Nos. 4,738,870 and 4,658,003 disclose hydroxyphosphinylalkyl(meth)acrylate as adhesion promoting monomers.
There is still a need for hydrolytically stable phosphorus-containing monomers, which may be incorporated into adhesive, coating or film compositions either by polymerization into the polymeric component of the composition or as a polymerizable additive per se. The incorporated monomers of the invention remain surprisingly hydrolytically stable in water-borne formulations such as latex while still retaining their adhesive properties.
This invention makes available hydrolysis-stable phosphorus-containing (meth)acrylamide monomers. These monomers can be polymerized using conventional radical initiators, photoinitiators and/or thermal initiators to give polymers with improved adhesive, flame retardant, scale inhibition, dispersing and/or anti-corrosive properties suitable for use in adhesives, paints and coatings, or plastics.